ci: add set -o pipefail and install log diagnostics

Author: zccrs

.github/workflows/dtkdeclarative-archlinux-build.yml

@@ -61,6 +61,7 @@ jobs:
 
       - name: Configure dtkdeclarative
         run: |
+          set -o pipefail
           cmake -B build \
             -GNinja \
             -DCMAKE_INSTALL_PREFIX=/usr \
@@ -85,6 +86,7 @@ jobs:
 
       - name: Build dtkdeclarative
         run: |
+          set -o pipefail
           cmake --build build -j$(nproc) 2>&1 | tee /tmp/cmake-build.log
           echo "✅ dtkdeclarative Qt${{ matrix.qt_version }} built successfully!"
           echo "=== Built files ==="
@@ -101,10 +103,20 @@ jobs:
 
       - name: Install dtkdeclarative to staging directory
         run: |
-          DESTDIR=/tmp/dtkdeclarative-install cmake --install build --verbose
+          set -o pipefail
+          DESTDIR=/tmp/dtkdeclarative-install cmake --install build --verbose 2>&1 | tee /tmp/cmake-install.log
           echo "Total: $(find /tmp/dtkdeclarative-install -type f | wc -l) files"
           find /tmp/dtkdeclarative-install -type f | head -20
 
+      - name: Print install log on failure
+        if: failure()
+        run: |
+          echo "=== cmake-install.log (last 80 lines) ==="
+          tail -80 /tmp/cmake-install.log 2>/dev/null || echo "(not found)"
+          tail -20 /tmp/cmake-install.log 2>/dev/null | while IFS= read -r line; do
+            echo "::error::$line"
+          done
+
       - name: Create installation package
         run: |
           ls -la /tmp/dtkdeclarative-install/ || { echo "Install dir missing!"; exit 1; }